How do I export a video from Blender?
assuming you have the video all cut together in the video sequence editor pannel, open a properties panel and go the the render section (first button with a picture of a camera) there will be all your render setting whch you may personalize. For rendering 3D you would want to first export as PNG files and then post render bring the PNG sequence into the Video sequence editor render it into a final video file, but it sounds like you are trying to do a final video render in which case you go to the output section and choose FFMPEG video, Then under encoding > container you generally want to go with either Quicktime (.mov) or mpeg-4 (.mp4) and for the codec use H.264